2. A history of that clause, as traced in the printed journal
of the Federal Convention, will throw light on the subject.

It appears that the clause, as it originally stood, simply
expressed "a power to lay taxes, duties, imposts, and excises,"
without pointing out the objects; and, of course,
leaving them applicable in carrying into effect the other
specified powers. It appears, farther, that a solicitude to
prevent any constructive danger to the validity of public
debts contracted under the superseded form of government,
led to the addition of the words "to pay the debts."

This phraseology having the appearance of an appropriation
limited to the payment of debts, an express appropriation
was added "for the expenses of the Government,"
&c.

But even this was considered as short of the objects for
which taxes, duties, imposts, and excises might be required;
and the more comprehensive provision was made
by substituting "for expenses of Government" the terms of
the old Confederation, viz.: and provide for the common
defence and general welfare, making duties and imposts,
as well as taxes and excises, applicable not only to payment
of debts, but to the common defence and general welfare.